Animate widget geometry inside layout

Hello,
I have a problem with animating widget which is placed inside layout. The struct is like fallowing:
@
mainWidget with HBoxLayout
{
animatedWidget
otherWidget
verticalSpacer
}
@

When I decrease the animatedWidget height, the layout does not refresh - otherWidget's top position is always the same, no matter which sizePlicy of animatedWidget do I choose. What is more, when I resize the window, the animatedWidget's height increases to the start value.